An animal model of Gaucher disease could be of great value in studying treatment strategies and some features of the pathogenesis of the disease. However, attempts to create such a model have been unsuccessful. The knockout mouse proved to be lethal at about the time of birth. We have now created a murine model of Gaucher disease by creating a chimeric mouse, transplanting wildtype mice with liver-derived hematopoietic stem cells from knockout fetuses. The peripheral blood and spleen from these animals is deficient in glucocerebrosidase activity and the amount of glucocerebroside in the liver and spleen is increased. Moreover, intravenous loading of the animals with glucocerebroside/albumin given intravenously increases the glucocerebroside levels further. We propose to further exploit this model by studying the natural history of glucocerebroside accumulation and by attempting to load these animals in a more convenient and possibly more physiologic manner. Such loading techniques might consist of intraperitoneal injection of glucocerebroside or the increase of blood cell turnover by the administration of G-CSF or phenylhydrazine. A "readout" that is more facile than chemical determination of glucocerebroside by HPLC will also be explored. In particular, electron microscopy and light microscopy will be used to attempt to demonstrate the development of Gaucher cells in the chimeric mice.